Predetermined torque release socket



Jan. 24, 1956 a. G. wooDs PREDETERMINED TORQUE RELEASE SOCKET WRENCH Filed Feb. 15, 1954 v N@ ww United States Patent l' The present invention relates generally to wrenches and more particularly to an improved form of adjustable torque wrench.

A very large number of adjustable torque wrenches are undergoing daily ally, engaging member and ment of the load-engaging member, until a desired amount of torque is applied thereby. The imposition of such torque upon the load-engaging member overcomes the force of the spring and the latter is deformed, thereby permitting a limited movement of the loadengaging member to occur. Such movement provides an indication that a desired amount of torque has been applied to the load.

After a certain amount of usage, it becomes necessary to replace the original spring with a new one. This involves a major difficulty, because of the wide variation in spring rates encountered with commercially available springs. While all springs of a similar commercial classication ostensibly have identical characteristics, as a practical matter this is not true. The spring rates of such springs actually vary widely from one another. Because of such spring rate variation, it s often impossible to satisfactorily eiect calibration of the wrench by adjustment of the spring alone.

It is a major object of the present invention to provide an adjustable torque wrench having novel means to compensate for the Wide variation in the spring rates of commercially available springs.

Another object is to provide an extremely accurate adjustable torque wrench of compact size and light weight which is economical of construction.

A further object of the invention is to provide an adjustable torque wrench having means for varying the amount of spring force being applied to the load-engaging Accordingly, the Wrench may be utilized even under conditions of darkness.

An additional object is to provide an adjustable torque wrench which is simple of design and rugged of construction whereby it may afford a long and useful service life.

These and other objects and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof, when taken in conjunction with the appended drawing wherein:

Figure 1 is a top view of an adjustable torque wrench embodying the present invention, which view is partly broken away in horizontal section;

Figure 2 is a fragmentary view similar to Figure l, but showing the parts of the Wrench disposed in a different position;

Figure 3 is a reduced wrench;

side elevational view of said Figure 4 is a vertical sectional view taken on line 4 4 of Figure l;

Figures 5 and 6 are vertical sectional views taken on line 5-5 of Figure 1 and showing the relative movement of the parts thereof as the torque setting of the wrench is being adjusted; and,

Figure 7 is an enlarged view of a detail of Figures 5 and 6.

Referring to the drawings, the preferred form of wrench embodying the present invention broadly comprises a head l0, a

A stop element Sil is formed at one side of the head interior for restraining counter-clockwise movement of the arm l5 beyond its position of Figure 2. The rear of the head l@ is formed with a threaded bore 32 wherein is disposed an externally threaded adjustment bushing 34.

rthe adjustment ,bushing 34 slidably encompasses a 44 of the lever 12. A pad element 46 may be interposed between the front of the spring 18 and the rear of the plunger 36.

boss 56 that supports the rear end of the spring l. Accordingly, rotation of the handhold upon the lever will effect expansion or contraction of the spring and thereby vary its compressive force.

ln operation, the socket 28 is engaged with a load, such as the bolt head 29 and the lever l2 is urged in a clockwise direction from its position of Figure l. As torque is applied to the bolt head, the shaft 25 and its attached arm 16 tend to rotate in a counter-clockwise direction from their position of Figure l. This tendency is resisted the spring 18 acting against It should be understood that the amount of torque applied to the bolt head 29 before the arm 16 undergoes initial counter-clockwise movement is controlled by the compressive force being exerted by the spring 13 against the rear end of the plunger 36. This compressive force is in turn controlled by the relative positions of the handhold 13 and the lever 12.

In order to provide a visual indication of the relative positions of the handhold 13 and the lever 12, the front of the handhold integrally mounts an index ring 60 having scaler markings 62 adapted to be utilized in conjunction with complementary Scaler markings 64 formed on the lever. These markings 62 and 64 may constitute Vernier graduations reading in foot-pounds and should be so coordinated with the spring rate of spring 18 and the geometry of the wrench as to provide an indication of the amount of torque being applied by the load-engaging member 14 when the arm 16 begins a counter-clockwise movement. Hence, before a bolt-tightening operation is started, the handhold 13 is rotated upon the lever 12 until the markings 62 and 64 are set at the desired footpound reading.

Under certain circumstances, e. g., during a military operation, it may be necessary that the wrench be utilized under conditions of darkness. Accordingl, the preferred form of wrench incorporates means for providing the operator with an indication of the settings of vernier graduations 62 and 64 that may be recognized by either his sense of hearing or of touch. Referring to Figures and 6, a lock ring 66 is journaled by the front portion of the handhold 13 for relative rotation thereon. This lock ring 66 is formed with a pocket 68 that extends radially outwardly from one point on its inner periphery. The portion of the lever 12 underlying the locks ring 66 is formed with a plurality of circumferentially-spaced axially extending grooves '70. These grooves 70 are adapted to receive the inner end of a locking button 72 that is slidably disposed within a bore 74 formed in the handhold 13. As shown in Figure 7, this locking button 72 is generally T-shaped in side elevation, having a generally cylindrical shank 76 and a head 78. The opposite end of the shank 76 is of rounded configuration corresponding to the curvature of the lever grooves 7i). A spring finger 80 is retained at one of its ends by the handhold 13. The free end of this spring finger Sil is constantly biased radially outwardly and it is also in constant engagement with the head 78 of the locking button.

When the aforedescribed parts are disposed in their positions of Figure 5, the shank 76 of the locking button 72 will be disposed within one of the lever grooves 70 so as to lock the handhold 13 and lever 12 against relative rotation. The locking button 72 is: retained within this lever groove by virtue of the fact that the intermediate portion of the spring nger 30 is in abutment with the shallow portion 82 of the lock ring pocket 68 whereby its free end is held in a radially inwardly disposed position. In order to permit the handhold 13 to rotate relative to the lever, the lock ring 66 is rotated slightly in a counter clockwise direction from its position of Figure 5 to that of Figure 6 so as to dispose the deep portion 84 of the pocket 63 adjacent the intermediate portion of the spring finger 80. The free end of the spring finger will then flex radially outwardly so as to free the locking button 72 for radially outward movement. Such movement will occur when the handhold is rotated upon the lever; the sides of the lever groove 70 exerting a camming action upon the shank 76. As long as the lock ring 66 remains in its position of Figure 6, the rounded end of the shank 76 will ride upon the outer periphery of the lever 12, dropping into each of the grooves 7 0 and subsequently rising therefrom. The movement of the locking button into and out of each of these grooves is accompanied by a clearly audible clicking sound, and additionally, it may readily be felt by the operator. Y Conveniently, the distance bctween the grooves 70 can be so selected that each click will indicate a definite change in foot-pounds or inchpounds.

As noted previously hereinbefore, it is necessary to cali brate the wrench for the particular spring 18 being utilized therewith. The present invention contemplates means for effecting such calibration. This means includes the adjustment bushing 34, the plunger 36, the ball 40 and the roller 42.

Referring to Figure l, it should be noted that the initial point of contact between the ball 40 and the roller 42 controls the amount of force being applied to the ball by the roller during a bolt tightening operation. Thus, assuming that a constant counterclockwise force were to be applied to the arm 16 through the socket 28, and the point of contact between the ball and the roller should be moved to the left in Figure l, the amount of rightwardly-directed force being applied to the ball by the roller would increase. This results from the fact that the wedging angle between the roller and ball would be reduced as this point of contact moves to the left. Because of such increase, an increased amount of compressive force would have to be exerted by the spring 18 against the plunger cap 38 in order to prevent initial counter-clockwise arm movement. Conversely, if the point of contact between the ball 40 and the roller 42 is moved to the right relative to its original position less compressive spring force would be required in order to prevent such initial arm movement. Accordingly, it will be observed that by varying the position of the point of contact between the roller and the ball, the mechanism may be adjusted to provide the same torque per unit of spring compression regardless of a variation in the spring rate of the particular spring being utilized. The point of contact between the ball 40 and the roller 42 is readily varied by screwing the adjustment bushing toward or away from the roller.

Referring to Figure 4, it should be particularly noted that the adjustment bushing 34 is formed with a polygonal passage for carrying the plunger 36. This affords at least a two point contact between the plunger and the bushing and thereby permits a lower unit loading than if the passage 90 were of circular cross-section. The voids 92 in the passage also permit air to pass between the interior of the head and the lever bore 44 during a torque applying operation without interfering with the lubrication of the plunger and without effecting compression of the air contained within the contines of the lever 12.

From the foregoing description, it will be apparent that there has been provided an effective and useful adjustable torque wrench which may be readily calibrated to different spring rates. It will be further apparent that various modifications and changes may be made with respect to the preferred embodiment of the wrench without departing from the spirit of the invention or the scope'of the following claims.

I claim:

l. An adjustable torque wrench, comprising: a head; a load-engaging member pivotally mounted at the front of said head', a lever extending away from the rear of said head; an arm member rigidly secured to said loadengaging member and extending' rearwardly therefrom; a roller carried by the free end of said arm; an adjustment bushingcarried by the rear of said head and having a passage; a plunger slidably disposed within said passage for movement toward and away from said roller; a ball disposed within the front portion of said passage and at the rear portion `of said roller; resilient means for constantly biasing said plunger forwardlytoward said roller; and means for adjusting said bushing toward and away from said roller.

2. An adjustable torque wrench, comprising: a head, a load-engaging member pivotally mounted at the front of said head; a lever extending away from the rear of said head; an arm member rigidly secured to said leadmeans for varying the compressive force of said spring.

3. An adjustable torque a load-engaging member pivotally mounted at the front of said head; a lever extending away from the rear of said head; an arm member rigidly secured to said loadengaging member; a backing element for retaining said abutment member in engagement with the free end ef said arm, said backing element being movably mounted movement of said handheld along said lever; a compression spring interposed between the rear of said backing element and said handheld; a lock ring jeurnaled upon said handheld and having a pocket that includes a shallow and a deep portion; a plurality of circumferentially-spaced axially extending grooves formed in said lever adjacent said lock ring; a bore formed in said handheld underlying said lock ring; a locking button formed with a shank that is slidably disposed in said bere for movement in a radial direction, and a head disposed outwardly of said bore; and a spring movement of said handheld 'said lever adjacent said lock along said lever; a compression spring interposed between the rear ef said plunger and said handheld; a lock ring journaled upon said handheld and having a pocket that includes a shallow and a deep portion; a plurality of circumferentially-spaeed axially extending grooves formed in ring; a bore formed in said handheld underlying said lock ring; a locking button a shank that is slidably disposed in said bere cent the deep portion et said pocket whereby said handhold may be rotated relative to said lever.

n. In an adjustable torque wrench having a head, a

along said lever, and a spring interposed between said head and said handheld, the combination of: a lock ring jeurnaled upon said handheld and having a pocket that includes a shallow and a deep portion; a plurality of circumferentially-spaced axially exably `disposed in said bore for movement in a radial direction, and a handheld and having its other end in contact with the head of said locking button, said spring normally being biased radially References Cited in the file of this patent UNITED STATES PATENTS 2,172,561 Kruse Sept. 12, 1939 2,662,436 Harmes Dec. 15, 1953 2,667,800 Garwoed Feb. 2, 1954 2,680,982 Poutot June 15, 1954 FOREIGN PATENTS 109,874 Australia Feb. 20, 1940 717,570 Germany Feb. 17, 1942 885,795 France June 7, 1943 

